Home Medizin Mikroplastik und Nanoplastik könnten Ihrer Herzgesundheit schaden

Mikroplastik und Nanoplastik könnten Ihrer Herzgesundheit schaden

von NFI Redaktion

In a recent study published in the New England Journal of Medicine, researchers investigated the presence of micro- and nanoplastics (MNPs) in atherosclerotic plaques.

Study: Microplastics and Nanoplastics in Atheromas and Cardiovascular Events. Image Source: chayanuphol/Shutterstock.com

Study: Microplastics and Nanoplastics in Atheromas and Cardiovascular Events. Image Source: chayanuphol/Shutterstock.com

Background

The production of plastics is increasing steadily and is projected to continue until 2050. Plastics can degrade and form MNPs, leading to toxic effects.

Studies have shown the entry of MNPs into the body through skin exposure, inhalation, and ingestion, as well as their interactions with tissues/organs. MNPs have been detected in placenta, liver, lungs, urine, blood, and breast milk. Current preclinical reports suggest that MNPs are a cardiovascular risk factor.

In vitro studies indicate that some MNPs promote inflammation, oxidative stress, and apoptosis in endothelial cells. Animal studies also support the role of MNPs in myocardial fibrosis, endothelial dysfunction, and impairment of heart function.

However, their clinical relevance remains unknown. There is no evidence of MNPs infiltrating human vascular lesions or a link between MNP exposure and cardiovascular diseases.

About the Study

In this study, researchers investigated the presence of MNPs in atherosclerotic plaques and the associations between MNP exposure and cardiovascular events.

Consecutive patients aged 18–75 years with asymptomatic carotid stenosis requiring carotid endarterectomy were examined. Patients with valve defects, secondary causes of hypertension, malignancies, or heart failure were excluded.

Patients who experienced complications in the postoperative phase were also excluded. Clinical baseline examinations were conducted, and access was obtained to health records for clinical, demographic, and intervention data.

Fasting blood samples were collected for biochemical analyses. Participants were followed up after carotid endarterectomy.

During atherectomy, surgically excised atheromatous plaque samples were obtained. MNP frequency was measured using pyrolysis gas chromatography-mass spectrometry and validated with electron microscopy (EM) and isotope analysis.

The primary endpoint was a combination of non-fatal stroke, non-fatal myocardial infarction, or death. Patients were categorized into groups based on the presence/absence of MNPs in plaques.

A Cox regression was performed to assess the associations between the presence of MNPs in plaques and the incidence of composite endpoints.

Analyses were adjusted for gender, age, body mass index (BMI), creatinine, low- and high-density lipoprotein cholesterol, total cholesterol, triglycerides, hypertension, diabetes, and previous cardiovascular events.

Results

The team examined 312 patients, of whom 47 could not be followed up or had missing data, and eight experienced a stroke or died before discharge.

A total of 257 participants were followed up for an average of 33.7 months. Polyethylene was detectable in the excised carotid plaques of 150 patients; thirty-one of them also had measurable amounts of polyvinyl chloride in the plaque.

The average content of polyethylene and polyvinyl chloride in plaques was 21.7 μg/mg and 5.2 μg/mg, respectively.

Patients with these MNPs were younger, male, smokers, had dyslipidemia, cardiovascular diseases, diabetes, higher creatinine levels, and had a lower risk of hypertension compared to patients without MNPs.

Ten random plaque samples with polyvinyl chloride and polyethylene were analyzed using EM. Transmission electron microscopy (TEM) showed particles (foreign in origin) smaller than a μm with jagged edges in foamy macrophages.

Additionally, the same sections were observed with scanning electron microscopy (SEM), and spectral X-ray maps of particles were created, resembling those observed with TEM.

The maps showed reduced carbon and oxygen content in plaque samples and increased chlorine content. Given the likely non-biological nature of chlorine, this could indicate polyvinyl chloride deposits.

Isotope analysis was conducted on 26 random plaque samples since petroleum-derived plastics have lower δ13C values, i.e., the ratio between carbon-13 and carbon-12, than human tissue.

This analysis revealed two distinct patient groups. One cluster comprised patients with higher δ13C values; the other cluster showed lower values, possibly due to MNP contamination. Lower values were more evident in plaques with MNPs.

The primary endpoint event occurred in 30 and eight patients with and without evidence of MNPs, respectively. Patients with MNPs in plaques had a higher risk of primary endpoint events than patients without MNPs.

Conclusions

In patients with high-grade asymptomatic carotid stenosis requiring carotid endarterectomy, the incidence of the composite endpoint was higher in patients with MNPs in plaques compared to those without MNPs.

Notably, the results do not prove causation; the association between MNPs in plaques and the primary endpoint could also entail risks from exposure to unmeasured, residual, or other confounding variables.

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